This application is based on Japanese Patent Application No. 2001-107243 filed on Apr. 5, 2001, the contents of which are incorporated hereinto by reference.
1. Field of the Invention
The present invention relates in general to a device for adjusting an angular position of an object about an axis or centerline of the object, and more particularly to reduction in size of the device.
2. Discussion of Related Art
For example, an angular position adjusting device is provided in an electric-component mounting device, and is used to adjust the angular position of an image-taking device. The image-taking device is used, for instance, to take an image of an electric component as held by a component holding device, for detecting positioning errors of the electric component as held by the component holding device, on the basis of image data indicative of the image of the electric component. The image-taking device is rotated about its axis or centerline, by the angular position adjusting device, so that an imaging area on which the image is formed is rotated about the axis of the image-taking device. The imaging area is perpendicular to the axis and has a center on the axis. By rotating the image-taking device, the angular position of the imaging area about its axis can be adjusted as desired, in order to prevent a detecting error of the positioning errors of the electric component on the basis of the image data, which detecting error takes place due to an angular positioning error of the imaging area of the image-taking device.
A known angular position adjusting device to adjust the angular position of the image-taking device includes a fitting portion formed on a first bracket holding the image-taking device, and has a fitting hole formed in a second bracket which holds the first bracket. The fitting portion has a circular cross sectional shape, and is coaxial with the axis of the image-taking device, having a diameter larger than that of the image-taking device. The fitting hole also has a circular cross sectional shape, and the fitting portion is slidably fitted in and guided by the fitting hole at an outer circumferential surface of the fitting portion and an inner circumferential surface of the fitting hole. The angular position adjusting device includes a rotating device operable to rotate the first bracket relative to the second bracket about the axis of the image-taking device, for thereby rotating the image-taking device about axis, so as to adjust the angular position of the image-taking device. Thus, the angular position adjusting device uses the fitting portion and the fitting hole which engage each other such that the fitting portion and hole are rotatable relative to each other.
The known angular position adjusting device is associated with the entire circumference of the image-taking device, and therefore tends to be relatively large-sized, requiring a comparatively large space for installation of the image-taking device. Accordingly, the known angular position adjusting device lowers the freedom of designing of component members surrounding the image-taking device, and may make it difficult to suitably install the image-taking device.
While the angular position adjusting device as applied to the image-taking device used in an electric-component mounting system has the above-indicated drawback, a similar drawback is encountered where the angular position adjusting device is used for an image-taking device in other systems, and for adjusting the angular position of any object other than the image-taking device, which objects has an axis or centerline.
It is therefore an object of the present invention to reduce the size of an angular position adjusting device. This above object may be achieved according to any one of the following modes of the present invention in the form of an angular position adjusting device, a position adjusting device, and an electric-component mounting system. Each of the following modes of the invention is numbered like the appended claims and depends from the other mode or modes, where appropriate, to indicate and clarify possible combinations of elements or technical features. It is to be understood that the present invention is not limited to the technical features or any combinations thereof which will be described for illustrative purpose only. It is to be further understood that a plurality of elements or features included in any one of the following modes of the invention are not necessarily provided all together, and that the invention may be embodied without some of the elements or features described with respect to the same mode.
(1) An angular position adjusting device for adjusting an angular position of an object about an axis of rotation of the object, the angular position adjusting device comprising:
a first member which holds the object;
a second member which holds the first member such that the first member is rotatable about the axis of the object; and
a rotating mechanism interposed between the first and second members, and operable to rotate the first member relative to the second member about the axis,
and wherein the second member has an arcuate guiding surface formed to extend along an arc of a circle having a center at the axis of rotation of the object, the arc having a center angle smaller than 180xc2x0, and the first member has a guided surface for sliding contact with the arcuate guiding surface to guide a rotary movement of the first member by the rotating mechanism relative to the second member, for rotating the object about the axis.
Each of the guiding and guided surfaces may be a part-cylindrical surface having a predetermined radius of curvature (a predetermined distance from the axis of rotation of the object), an inclined surface whose radius of curvature continuously changes in the axial direction of the object, or a stepped part-cylindrical surface having two or more radii of curvature.
When the first member is rotated by the rotating mechanism about the axis of the object, to adjust the angular position of the object, the guided surface is guided by the guiding surface so that the object is rotated about its axis. The center angle of the arc of the arcuate guiding and guided surfaces is smaller than 180xc2x0 of the circle having its center at the axis of rotation of the object. Accordingly, the angular position adjusting device is disposed along only a part of the periphery of the object and can be made comparatively compact, so that the required space for installing the object together with the angular position adjusting device can be reduced, leading to an increased freedom of designing of the component members surrounding the object and simplification of a device or system provided with the object, or making it possible to provide a compact device or system with the object such that the angular position of the object is adjustable.
Further, the angular position of the object can be adjusted by rotating the object about its axis, without a deviation of the axis from the nominal position. Thus, the angular position can be adjusted with high efficiency, without calculating an amount of such a deviation and re-establishing the nominal position of the axis of the object.
Since the angular position adjusting device can be made compact as described above, the sizes of the workpieces to be machined to manufacture the angular position adjusting device can be made accordingly small, and the required time of machining the workpieces can be shortened.
(2) The angular position adjusting device according to the above mode (1), further comprising a biasing device interposed between the first and second members and operable to bias the first and second members toward each other, for pressing contact of the guiding and guided surfaces with each other.
Since the guiding and guided surfaces are held in pressing contact with each other, the axis of rotation of the object is not moved in a plane perpendicular to the axis, when the first member is rotated relative to the second member. Accordingly, the angular position of the object can be adjusted with a high degree of accuracy.
(3) The angular position adjusting device according to the above mode (1) or (2), wherein the guiding surface formed on the second member is a part-cylindrical concave surface while the guided surface formed on the first member is a part-cylindrical convex surface.
The part-cylindrical concave surface and the part-cylindrical convex surface may be respectively one of opposite part-cylindrical surfaces of an arcuate groove, and one of opposite part-cylindrical surfaces of an arcuate protrusion. Alternatively, the part-cylindrical concave and convex surfaces may be stepped part-cylindrical cylindrical surfaces.
(4) The angular position adjusting device according to the above mode (2) or (3), wherein the biasing device includes:
a ball;
a ball holder holding the ball such that the ball can roll and partly project from the ball holder but cannot be removed from the ball holder; and
an elastic member interposed between the ball and the ball holder and biasing the ball in a direction for the ball to project from the ball holder,
and wherein the ball holder is fixed to one of the first and second members, such that the ball is held in pressing contact with a part-cylindrical surface which is formed on the other of the first and second members, so as to extend along an arc of the above-indicated circle having the center at the axis of rotation of the object.
When the first member is rotated, the biasing device is moved relative to the other of the first and second members, while biasing the first and second members toward each other in a direction substantially parallel to the radial direction of the object. The ball is held in pressing contact with the part-cylindrical surface of the above-indicated other member, and is moved in rolling contact with this part-cylindrical surface when the first member is rotated. The rolling contact of the biasing device at its ball with the part-cylindrical surface is effective to reduce an amount of wear of the part-cylindrical surface, resulting in a prolonged life of the angular position adjusting device.
(5) The angular position adjusting device according to the above mode (2), wherein one of the first and second members has an arcuate groove having a substantially rectangular shape in cross section taken in a plane which is parallel to a radial direction of the object and which includes the axis of rotation of the object, and the other of the first and second members includes an arcuate protrusion received in the arcuate groove, and wherein one of opposite arcuate surfaces of the arcuate groove and one of arcuate opposite surfaces of the arcuate protrusion which is opposed to the above-indicated one of the opposite arcuate surfaces of the arcuate groove are forced against each other with a biasing force of by the biasing device and serve as one and the other of the guiding surface and the guided surface.
In the angular position adjusting device according to the above mode (5), portions of the guided and guiding surfaces which receive the biasing force of the biasing device are located in a plane perpendicular to the axis of rotation of the object, so that the guided and guiding surfaces are held in pressing contact with each other, without the biasing force of the biasing device causing a moment to rotate the first member about an axis perpendicular to the axis of rotation of the object. The first and second members may receive the biasing force at different positions which are spaced apart from each other in a direction parallel to the axis of rotation of the object, where suitable means is provided to prevent an inclination of the first member which would take place due to generation of the above-indicated moment. However, the provision of such means to prevent the inclination of the first member causes drawbacks such as an increase in the cost of manufacture of the angular position adjusting device. In the angular position adjusting device according to the above mode (5), the angular position of the object can be adjusted while the guiding and guided surfaces are kept in pressing contact with each other, without an inclination of the first member, so that the size of the angular position adjusting device can be reduced, without an unnecessary increase in the cost of manufacture.
Where the width of the arcuate protrusion is made smaller than that of the arcuate groove, a gap may be provided between the other of the above-indicated opposed surfaces of the arcuate protrusion and the other of the above-indicated opposed surfaces of the arcuate groove, so that the first member can be smoothly rotated with a reduced resistance of friction between the first and second members, while the guiding and guided surfaces are held in pressing close contact with each other.
(6) The angular position adjusting device according to the above mode (5), wherein the biasing device includes:
a ball;
a ball holder holding the ball such that the ball can roll and can partly project from the ball holder but cannot be removed from the ball holder; and
an elastic member interposed between the ball and the ball holder and biasing the ball in a direction for the ball to project from the ball holder,
and wherein the ball holder is fixed to one of the arcuate protrusion and a portion of the above-indicated one of the first and second members which portion has the other of the opposite arcuate surfaces of the arcuate groove, the ball holder being fixed so as to extend in a substantially radial direction of the arcuate protrusion and groove, and wherein the ball is held in pressing contact with one of the other of the opposite arcuate surfaces of the arcuate protrusion and the other of the opposite arcuate surfaces of the arcuate groove.
The ball is held in pressing contact with at least one of the arcuate surface of the arcuate protrusion which is not the guiding or guided surface, and the arcuate surface of the arcuate groove which is not the guiding or guided surface. Since the ball holder is fixed so as to extend in the substantially radial direction of the arcuate protrusion and groove, the ball is pressed against the appropriate arcuate surface in a direction normal to this arcuate surface, so that the biasing force of the elastic member is effectively applied to the arcuate surface.
(7) The angular position adjusting device according to the above mode (6), wherein the ball is held in pressing contact with the other of the opposite arcuate surfaces of the arcuate protrusion, and this other arcuate surface of the arcuate protrusion is inclined such that a distance between the opposite arcuate surfaces of the arcuate protrusion decreases in a direction from a free end toward a fixed end of the arcuate protrusion.
The inclination of the arcuate surface of the arcuate protrusion causes a force to act on the first member in the axial direction of the object such that the first member is moved toward the second member, so that the first and second members are forced against each other in the axial direction of the object. Thus, the inclination of the arcuate surface of the arcuate protrusion prevents a movement of the first member away from the second member in the axial direction, so that the first member can be rotated relative to the second member with high stability.
The technical feature according to the above mode (7) is applicable to the angular position adjusting device according to the above mode (4).
(8) The angular position adjusting device according to the above mode (6), wherein the ball is held in pressing contact with the other of the opposite arcuate surfaces of the arcuate groove, and this other arcuate surface of the arcaute groove is inclined such that a distance between the opposite arcuate surfaces of the arcuate groove decreases in a direction from a bottom toward an opening of the arcuate groove.
The angular position adjusting device according to the above mode (8) has the same advantage as described above with respect to the above mode (7). The technical feature according to the above mode (8) is also applicable to the angular position adjusting device according to the above mode (4).
(9) The angular position adjusting device according to any one of the above modes (1)-(8), wherein the first and second members have respective contacting surfaces which are held in contact with each other in an axial direction of the object, for positioning the first and second members in the axial direction.
(10) The angular position adjusting device according to the above mode (9), further comprising a tightening device operable to force the first and second members against each other ins the axial direction for increasing a pressure of contact of the contacting surfaces.
(11) The angular position adjusting device according to any one of the above modes (1)-(10), wherein the first and second member and the rotating mechanism are provided for each of a plurality of objects which are arranged such that axes of rotation of the objects extend in parallel with each other in a plane and are spaced apart from each other at a predetermined spacing pitch in a direction parallel to the above-indicated plane and perpendicular to the axes, the first members for the plurality of objects being arranged in the direction parallel to the above plane and perpendicular to the axes of the object, while the second members for the plurality of objects being similarly arranged in the direction parallel to the above plane and perpendicular to the axes.
The first members corresponding to the plurality of objects are disposed so as to extend in a direction perpendicular to the plane in which the axes of the objects lie. Similarly, the second members corresponding to the objects are disposed so as to extend in the above-indicated direction. Accordingly, a plurality of sets of the object, first member and second member may be arranged adjacent to each other without a gap or with only a small amount of gap, in the direction which is parallel to the plane including the axes of the object and which is perpendicular to the axes. Therefore, a system including the plurality of objects and the angular position adjusting device can be made compact.
(12) The angular position adjusting device according to any one of the above modes (1)-(11), wherein the object is an image-taking device.
(13) A position adjusting apparatus comprising:
an angular position adjusting device as defined in any one of the above modes (1)-(12); and
at least one of (a) a first-direction position adjusting device operable to adjust a position of the object in a first direction parallel to an axial direction of the object, (b) a second-direction position adjusting device operable to adjust a position of the object in a second direction which is parallel to one of two mutually perpendicular directions which are perpendicular to the first direction; and (c) a third-direction position adjusting device operable to adjust a position of the object in a third direction which is parallel to the other of the two mutually perpendicular directions.
(14) An electric-component mounting system comprising:
a substrate holding device operable to hold a circuit substrate;
a component supplying device operable to supply an electric component;
a component mounting device including a suction nozzle to hold the electric component by suction under a negative pressure, the component mounting device being operable to receive at the suction nozzle the electric component from the component supplying device, and to mount the electric component on the circuit substrate held by the substrate holding device;
an image-taking device operable to take an image of the electric component as held by the suction nozzle;
a first member which holds the image-taking device;
a second member which holds the first member such that the first member is rotatable about an axis of the image-taking device; and
a rotating mechanism interposed between the first and second members, and operable to rotate the first member relative to the second member about the axis,
and wherein the second member has an arcuate guiding surface formed to extend along an arc of a circle having a center at the axis of the object, the arc having a center angle smaller than 180xc2x0, and the first member has a guided surface for sliding contact with the arcuate guiding surface to guide a rotary movement of the first member by the rotating mechanism relative to the second member, for rotating the object about the axis of the image-taking device.
For instance, the circuit substrate may be selected from among: a printed-wiring board on which electric components (e.g., electronic components) have been mounted for none of printed wirings formed on an electrically insulating substrate; a printed-wiring board on which electric components have been mounted for some of the printed wirings: a printed-wiring board on which electric components have been mounted and soldered to the printed wirings; a circuit board on which small electric components are to be mounted; and a substrate on which are formed solder bumps for package electric components in which chips are enclosed in protective housings.
The component mounting device may include a component holding device, which includes the suction nozzle, or the suction nozzle and a nozzle holder holding the suction nozzle.
For instance, the component mounting device may be one of the following three types: (a) a device including a plurality of component holding devices, and a moving device in the form of a turning device operable to turn the plurality of component holding devices about a common axis of turning such that each of the component holding device is sequentially stopped at a plurality of working positions arranged along a circle having a center at the common axis of turning, so that the component holding device located at one of the working positions receives the electric component from the component supplying device, while the component holding device located another of the working positions transfers the electric component onto the circuit substrate; (b) a device including a component holding device movable in a plane parallel to the component mounting surface of the printed board, in two mutually perpendicular directions, and a moving device operable to move the component holding device in the above-indicated plane, to desired positions at which the component holding device receives the electric components from the component supplying device, so that the electric component is transferred from the component holding device onto the circuit substrate; and (c) a device including a component holding device movable in a plane parallel to the component mounting surface of the printed board, in one of two mutually perpendicular directions, and a moving device operable to move the component holding device in the above-indicated one direction, to receive the electric components from the component supplying device and mount the electric components onto the circuit substrate.
In the electric-component mounting system including the component mounting device of the type (a), the turning device may include a rotary body rotatable about an axis, and a rotating device operable to rotate the rotary body in a selected one of opposite directions by a desired angle. The rotary body carries the plurality of component holding devices, and is rotated to move each component holding device sequentially to the component-receiving position and the component-mounting position. The rotary body may be an rotated indexing body which is intermittently rotated by an intermittently rotating device and which carries the component holding devices such that the component holding devices are equiangularly spaced apart from each other in the rotating direction of the indexing body. In this case, each component holding device is sequentially stopped at the component-receiving and component-mounting positions by intermittent rotary motions of the indexing body. Alternatively, the turning device may include a plurality of rotary members arranged about a common axis of turning such that the rotary members can be turned about the common axis of turning, and a turning-motion applying device including a cam device operable to turn the rotary members about the common axis, at a speed controlled in a predetermined pattern, so that each rotary member is sequentially stopped at a plurality of working stations at different times. The rotary members carry the respective component holding devices such that each component holding device is rotatable about its axis and is axially movable relative to the rotary members, so that the component holding devices can be turned with the rotary members about the common axis of turning.
In the electric-component mounting system including the component mounting device of the type (a), the substrate supporting device includes a substrate supporting unit for supporting the circuit substrate, and a substrate moving device operable to move the substrate supporting unit in the plane parallel to the circuit substrate, in the two mutually perpendicular directions, while the component supplying device includes the two component supply tables, and a table moving device operable to move the component supply tables in a direction in which the component-supply portions of the plurality of component feeders of each table are arranged. In the component mounting system including the component mounting device of the type (b), the substrate supporting device and the component supply tables are fixedly disposed. In the component mounting system including the component mounting device of the type (c), the substrate supporting device includes a substrate supporting unit for supporting the circuit substrate, and a substrate moving device operable to move the circuit substrate supporting unit in the plane parallel to the circuit substrate, in one of the two mutually perpendicular directions in which the component holding device is not movable. In this third case, the component supply tables may be fixedly disposed such that the component holding device is movable to each of the component-supply portions of the component feeders. Alternatively, the component supply tables may be movable in the direction in which the component-supply portions of the component feeders are arranged. The component-supply portions of the component feeders may be arranged along a straight line, a curved line, a circular arc, or a line consisting of any combination of those lines and arc.
Where the component holding device is movable by the moving device in the plane parallel to the circuit substrate or along a straight line in this plane, another moving device may be provided to give the component holding device a supplemental or auxiliary motion. Where a plurality of component holding devices are carried by a rotary body (e.g., intermittently rotated indexing body), for instance, this rotary body may be arranged to be linearly movable by another moving device in two mutually perpendicular directions in the above-indicated plane, so that each component holding head is moved to a desired component mounting spot on the circuit substrate, by a combination of the rotary and linear motions of the rotary body. In this case, the axis of rotation of the rotary body may be either perpendicular or inclined to the plane in which the component holding devices are linear moved. The working position at which each component holding device carried by the rotary body receives the electric component from the component supplying device may be the same as or different from the working position at which each component holding device transfers the electric component onto the printed board.
The electric-component mounting system according to the above mode (14) can be made compact in construction, while permitting an adjustment of the angular position of the image-taking device.
(15) The electric-component mounting system according to the above mode (14), wherein a plurality of sets of the image-taking device, the first and second members and the rotating mechanism are arranged such that the axes of the image-taking devices extend in parallel with each other in a plane and are spaced apart from each other at a predetermined spacing pitch in a direction parallel to the above-indicated plane and perpendicular to the axes of the image-taking devices.
The electronic-component mounting system according to the above mode (15) can be made compact in construction, while permitting adjustments of the angular positions of the individual image-taking devices.
(16) The electronic-component mounting system according to the above mode (15), further comprising an optical guiding device including a light-receiving portion disposed so as to be in opposed relation with the suction nozzle, and a light-distributing portion arranged to distribute a light received by the light-receiving portion, to the plurality of image-taking devices.
(17) The electronic-component mounting system according to any one of the above modes (14)-(16), further comprising at least one of (a) a first-direction position adjusting device operable to adjust a position of the object in a first direction parallel to an axial direction of the object, (b) a second-direction position adjusting device operable to adjust a position of the object in a second direction which is parallel to one of two mutually perpendicular directions which are perpendicular to the first direction; and (c) a third-direction position adjusting device operable to adjust a position of the object in a third direction which is parallel to the other of the two mutually perpendicular directions.